Multioffice telephone system



July 6 1926. J. E. OSTUNI-2 MULTIOFFICE TELEPHONE SYSTEM' e sheets-sheet' 1 Filed oct. l8r,i 12122 Imm-1:1 U12 ffm EWE-11m J. E. @STL-INE MULTIOFFICE TELEPHONE SYSTEM Filed'oot. 1s, l1922 e sheets-Sheet 2 July e, 1926.

y ".l. E. os'TLlNE MULTIOFFICE TELEPHONE SYSTEM 'e sheets-sheet s Filed oct. 18, 1922 :Imeu Dr-4 Juhuv E- U''me July 6 1926.

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J. E. OSTLNE MULTIOFFICE TELEEHONE SYSTEM Filed Oct. 18, L922 6 Sheets-heet 5 l 5 l Jahn E lme l July 6,1926. J. E. OSTLINE MULTIOFFICE TELEPHONE SYSTEM v Filed oct. 18, 1922 e Sheetsh'etu 4 .Patented July 6, 1926.

UNITED Is'rivres JOHN E. OSTLINE, OF CHICAGO, ILLINOIS,

.SSIGNOR, BY MESNE ASSIGNMENTS,' T0

AUTOMATIC ELECTRIC INC., O15",011143'A..Gfv ('.)-,V ILLINOIS, A CORPORATION 0F DELA"- WARE.

MULTIOFFICETELEPHONE SYSTEM. i

Application led October 18, 1922. Serial No. 595,251.

The present invention relates to multioftice telephone systems in general, but 1s concerned more particularly with multi-otlice telephone systems in which there 'are both manual and automatic offices, and the principal object, briefly stated, is the provision ot new and improved circuit arrangements, whereby calls originating in an automatic office and intended for a subscriber Whose line terminates in a manual ollice may be handled in a desirable and efficient manner.

More specicallyLthe present invention provides a device, which will be termed hereinafter a coder, which is located in an auto matic otce, and which stores up the impulses representing the various digits in the desired sub'scribers number, and which transmits a corresponding series of coded impulses to the manual oiiice When the oper` tion.

In order to give a full understanding of the advantages of such an arrangement, the situation which necessitated the invention will be briefly reviewed. As is WelLknown, a type of automatic telephone switching equipment which is known as panel or machine switching equipment has been evolved for multi-oliice systems. When a step by step automatic oftice is installed in a multi-oliice system already containing manual and machine switching offices, it is desired to have all. the indicating devices'in the manual otlice the same, regardless of Whether the call is coming from a machine switching ollice or from a-step by step automatic oliice.

In the machine switching system, the subscriber`s number is received at the central office upon a device known as a sender, which sender directs the machine switches in accordance with the desired number. When-a system is installed in which there are machine switching oflices and manual oflices, the senders in the machine svitching otlices are arranged so as to trunk the call through to the desired manual oliice in the usual manner. and then to send a series of coded impulses to themanual oltice upon the response of the operator. These coded imator thereat is ready to set up the connecpulses cause the desired number to be dis played on the operators'set of display or call indicator lamps. Heretofore, calls from step by step a'uto- .handling calls,

'invention matic olilces to manual call indicator Jotlices have been handled by providing a plurality of register sets in each manual call indicator oiiice, Which registersets store up the desired numbers as they come in. The numbers are switched on to the common set of display lamps one at a. time,A as each preceding call is completed by the operator. Obviously, this system may be used in not only from step by step automatic oflices, but also from machine switching automatic otlices, but an investigation seems to .reveal that it is easier and more eflicient to arrange the step by step automatic equipment to send out the coded impulses. than it is to change the machine switching equipment to operate the call indicators according to the common practice setout above in connection With step .by step oiices.

' Accordingly, a number of coders suiicient4 to take care of the trailc are provided for each step by step automatic ollce, and when a trunk extending to a -manual office is seized, a coder is seized also. This coder responds to the digits in the desired number and sends out the corresponding coded impulses upon the responseofthe Voperator as is the practice in handling calls from machine switching automatic olices -to manual call indicator offices.

Referring now to the drawings compris-l .ing Figs.

1-10, inclusive, they can be understood best it Figs. l, 2, and 5 are laid out in order with the corresponding lines at the ends thereof in alignment;I with Figs. 3 and 4 arranged under Fig. 2 with the corresponding interconnecting lines at the edges thereof in alignment; and with Fig. 6 similarly placed under ig. 5. VVhenthus arranged, the drawings show by means'of the usual circuit. diagrams, `a suliicient amount of apparatus in a system embodying the principles of the invention to allowv the to be undertood thoroughly, when considered in connetion with the accompanying description. I

Referring now particularly to' Fig` 1, there is shown an automatic Whose line terminates in -the step by step automatic office in the line switch C, which line switch has access to a number of first selectors, such as E, throughl the Inedium'of substation A, l i

los

an equal number of trunk circuits, such as each operators position.

on one, Ievelto trunks to a manual oltice by 'ay ol' repeaters such as the repeater R, Fig, :2.

Associated ivtli each repeater such asv ll, there is a secondary switch `such as the secondary switch Sri. 'l`h'ese sivitchcs have common access to a number ot' coders, such as the coder shown in Figs.

'25 and l.

llach ot' the trunks extending 'troni the automatic ollice to the call indicator manual oilice suchv as the one comprising comluctors E3() and lill, terminates at the manual oliice in a single plug cord circuit, such as the cord circuit O.

In the manual oltice there is a registering device such as the one shown in Fig. (l 'at This device responds to the coded impulses which are sent inupon the depression ol an assignment key, such as K, by the operator when she sees the line lamp, such as L, lighted at the associated cord circuit. Vilben the coded impulses have all come in, the correct com binat'ion ot lamps in the lamp bank. Fig. 6 is lighted., whereupon 'the operator plugs up the number into the multiple. at the same time releasing hcr assignment key.

fhe line switch C, Fig. l. in which the line of substation A terminates is of tbe usual rotary type, in which the wipers have. no normal .position and move in a forward direction only. The secondary switches 5S, SS', andthe sender S. Figs. l, 2, and 4, respectively, are mechanically identical with the line switch C.

rlfhe automatic selectors such as E are mechanically of the Well-known vertical and rotary type and, accordingly, have one hundred sets ot bank contacts arranged in horizontal rows or levels.

The master digit control switch MDC,

Fig. 3,/is ot the so-called minor switch type. The wipers ot this switch are moved in one-plane only by the operating magnet 226, and are restored to normal by release magnet 227 under the joint control ot otl' normal contacts 228 and armature 'JOD vand its resting contact ot -release relay Bill, Each ot' thc-digit. register switches TDR-Dlt", in` clusiie. is mechanically identical wth the master digit coidLrol switch UDC, with the exception that the wipers oli the digit registers are normally standing oil' the bank. u bile the wipers oit the master digit control switch MDC are normally in engagement secondaryv desires to call a subscriber whose, line terniinatos in the manual call indicator otlice, the subscribe at substation A tor example. lt

will be assumed further that the manual call indicator oilice is listed in the directory as Ill), or the numerical equivalent thereof, and that the number assignedto the line ot sub-tation 2590, and that the. station designation is lV. Consequently, the number to be dialled is 35)-2390-lV. i

`When the receiver is removed at subst ation A, a circuit is closed ovenline conductors "2 and 4 tor line relay 6 ot' the line.

switch C. Line relay 6,' upon energizing,

places ground on private normal conductor in', at armature il, thereby making the calling'` line busy and closing a circuit for switching relay 5 and stepping magnet l2 in series.

Also, Irelay 5 at armature l() connects test wiper 1l to the junction otl switching relay 5 and stepping magnet l2. ln case the trunk upon which the wipers of the line switch are standing is idle, the operation et armature l() does not produce any ettect and switching relay 5 cnergizcs immediately. Assuming` the trunk to be busy, however, switching relay 5 isshort circuited by the ground potential encountered on the test contact ot the trunk by test Wiper 14 and does not energize. In this case, the Wipers 13-15, inelusive1 are advanced step by step in search of an idle trunk by the buzzer-like action of stepping magnet 19., which operates from ground picked up by test wiper 1li.

When an idle trunk is reached, which trunk it will be assumed is the one coinprising' conductors lll-Q1, inclusive. and terminating,r in bank contacts iti-18, inclusive, switching relay 5,being,no longer short circuii'ed. cnergizes in series with stepping magnet l. Stepping magnet 1Q, however. does not energize at this time on account ot the high resistance ot switching' relay Upon energizing, switcliing relay opens the test circuit and prepares the holding' circuit at armature t5, and at. armatures T and 9 'disconnects line conductors 2 and-al troni line relay (i and groundand extends them by way oi wipers i3 and l5. bank contacts lil and 18, conductors 19 and Q1, and armatures 35iand 36 to the windings ot line relay lll ot' the trunk circuit- TC. Line relay 31,. upon energizing, closes a circuit for yrelay 50 of the secondary switch SS at arma-` ture 38. Relay 50. uponenergizlng, places ground on release trunk conductor and disconnects said release trunk conductor i2() be assumed is the one comprising conducnamed seizure.

' tors (iS-71, inclusive,

and terminating in bank contacts 64-67, inclusive. Switching rela)1 51, upon energizing, when the idle trunk is selected, opens the test circuit and grounds release trunk conductor 69 at armature 57; grounds the discriminating conductor 68 at arn'iature 56; connects up the operating conductor 70 at armature 58; and at armature 59 yconnects up the `outgoing send-k ing conductor 71. Release relay 72 and discriminating relay 73 of the director to which the seized trunk extends, energize and perform the usual functions upon 'the above ing up of the outgoing sending conductor, repeating relay in the trunk circuitTC energizes and places a bridge across conduc- -tors 42 and 44 of the selector E at armature 41, Whereuponline reliy` 80 of the selector',

E energizes and closes a' circuit forreiease relay 81 at armature-90'. Release relay 81, upon energizing, prepares a circuit for vertical magnet 49 at armature 92, and at arma- 'ture 91 places ground on release trunk conductor 43. f K

In response to Athe connecting up of the operating conductor 7() ot' the director trunk,

the trunk tone is sent back Working contact of arn'iature 58 and said armature, land through the small condenser 40 in the trunk circuit'TC to the lower heavy talking conductor. Ias is disclosedin the Nelson application above referred to, to inform the ,calling subscriber that he may bcgin to dial the various digits in the. desired nulnber. W'hen the subscriber operates his ,calling'device in accordance with `the first` digit 3 in the number ot' the desired otiice, the circuit of line relay :il of the trunk circuit TC is opened a corresponding number of times at the calling substation. lUpon each deencrgization ot'. pulse of current is transmitted at armature 39 over the operating conductor 70 to the. operating circuit ot' the director` whereupon the director operates in the .usual manner to record the digit. lach of thet'ollo\ving digits is transmitted to the director in the saine manner. j

' When the two oilice ceived by the director, the sending portion In 'response lto the connect.

thro ugh the line relay 3l, an im-` digits liave been rein accordance with the first ollice digit, 1t opensl the circuit ot .line relay 8O at armature 4l. Upon each ot 75 lthe deenergizations ot' line relay 80 thereby produced, an impulse otcul-rent is' delivered to vertical magnet 19in wayot armature 92 and lts wor-klug Contact and series relay` S2. By the operation ot` vertical magnet 49. 8O

'the Wipers 1GO-102, inclusive. are raised oposite the desired lcvcl ol bank contacts.v glow acting series relayhz is maintained. energized in series with vertical maginptl if)` v throughout the vertical movement` and closes at armature 93 a 'circuit for stepping` relay 83 in series with ott' normal contacts` 89. which contacts close upon the first vertical step offthe switch. llpo'n energizing. steppingif'elay S3 closes` a locking` circuit for it` self at armature 94, and at armature 95 pre parcs a circuit for rotarymagnet So.

Series relay deenergizes upon the termination of thevertical movement and closes a circuit for rotary magnet Sti at armature 93,. Rotary magneten, upon energizing. advances the wipers 1GO-102. inclusive. intoengagement With the lirst set ot' bank contacts in the `level oppositowhich they are raised and, near the end ot its stroke. opens tno the circuit of stepping relay atfinterrupter .contacts yS8. Stepping' relay` 8?), upon deenergizing, opens the circuit ot rotary niagnet'at armature.y 95. Rotary magnety 86. upon deenergizingmloses its interruptt-r con.

tacts ,88, again.

Ifthetrunk terminating in the tiret. set.

of bankfvcontacts isidle, switching relay' 84;' i energizes immediately. However. it' the trunk is' busy, switching relay S- is short 110 circuitedA by the ground potentialk which is present on the test contact thereof, and step-V ping relay S3, upon energizing from this same source ot ground potential, closes a circuit for rotary magnetgbt again at armature 95, whereupon' the wipers are advanced into engagement. with the. next set ot bank contacts. 'lhis alternate operation of steppingfrelay @Land Irotary magnet 8G continues until an idle trunk is reached, whichtrunk fit will be assumed is the one terminating in bank contacts IUS-105. inclusive,` and extending to the second selector F.-. .`Whel said idle trunk is reached. fswitcl-iifg relay 84, being no longer shortcircuited, energizes 125,

switching relay 84. Switching relay 8,4, up-

on energlzing, removes ground from armbli holding circuit at armature 97; and at arrnatures 9G and 99 disconnects conductors 42 and 14 from the windings ofr relay 8O and extends them by way of wipers and 10:2 and bank contacts 103 and 105 to the line relay of the selector F. The line and re leaserelays (not shown) of the selector Fnow energize and the latter places ground on the associated release trunk conductor, thcreby establishing the usual holding circuit forv switching relay Set through bank contact 101, test wiper 101, working Contact heiore slow acting release relay 81 has had Atime to dcenergize.

then the second digit in the otiice number is sent out by the director, the line relay otl the selector l" isctnitrolled at arnmture 41 of repeating relay 32 ,to step the wipers of the Selector P" up to thc desired level of bank contacts, whereupon the trunk limiting operation tal-:es place, in the usual manner. lt will be assumed that the trunk compris ing conductors 11G-112, im.lnsive,-and extending to the manual exchange by way oi the repeater R the one selector l".

Upon the seizure of the associated trunk, line relay 111 of the repeater R energizes over conductors and 112 rand closes a circuit for release relay at armature 121. ielease relay 115, upon energizing, places ground on release trunk conductor 111 at armature 123, closes a circuit for the lower or polarizing winding ot electro-polarized relay v113 at armature 121, and at armature 122 closes a circuit for line relay 135 of the secondary` switch SSpby way of armature 128 and its resting contact and the normally closed contacts conti-oiled by armature 1.42. Line relay 111:3', upon energizing, closes a circuit for switching relay 136 and stepping magnet '1C-:ET in series at armature. 138, and at arnniture 13%) connects test wiper 11T to the junction ot'switehing relay 13G and stepping magnet 13T. The. se( mdary switch SS now selects an idle trunk in the usual manner, the trunk comprising conductors 153-156, inclusive, for e '\'ampl .v Switching relay 136, upon energizing when the idle trunk is selected. opens the test circuit and grounds release trunk conductor 15T at armature 111); connects up operating conductor 156 at: armature litt; connects up the outgoing impulse conductors 15C'. and 154 to trunk conductors 13o and v131 at arn'iatures 111) and lill: and at armature l-t closes a locking ycircuit t'or itself and opens the circuit ot' line relay 135. liine relay 135 now deenergizes. but. docs not produce any resultat thistime. v

'ln the coder. release relay 201. `Fig. 2i, energi-Zcs in `iespoiise to ground being placed and armature 97 and its.

seized by the on the conductor 155 by the secondary switch SS, as pointed out above. Upon energizing, relay 201 disconnects ground at one point trom the common conductor 163 at armature 207 and at armature 209 disconnects ground romrelease conductor 224 and places ground on Wiper 280 of the master digit control switch MDC. The coder is now ready to receive the digits in the snbscribers number. i

Vhen the director, Fig.'1, sends out the iii-st digit 2 in the subscribers number, rthe circuit ot' line relay 114 ot the repeater R is interrupted twice. Upon deenergizing in response to each of the two interruptions produced in its circuit, line relay 114 places ground on the operating conductor 156 at armature by way ot' the working contact oft" armature 144 and said armature, wiper 118, and bank contact 151.. The etect ci this is to send two impulses ot' current to the operating magnet 221 of the digit register DR, Fig. 3', the circuit being as previously traced to operating conductor 156, and thence by way of series relay 202, wiper 229 of the master digit control switch MDC, the tirst associated bank contact, and operating magnet 221 of the digit register DR to battery. By the operation of magnet 2:21, the wipers 231 and 232 of the digit register DR are advanced into engagement with the second set of associated bank conacts. Relay 202 is energized in series with magnet Q21., and, being slow acting, retains its armature attracted throughout the series of impulses. Upon energizing, relay 202 closes a circuit for slow acting relay 203. Relay 203, upon energizing, prepares ya cir-- cuit for operating magnet 226 et' the master digit control switch MDC at armature 211.

At the end of the. series of im ulses, relay :202`deenergizes and opens t e circuit of relay 203 at armature l210. Relay 2015, however, being slow acting, retains its armature attracted for an interval. As'afurther result of the deenergization of relay i202, it completes the circuit of operating magnet 926 at armatureA 210 by way of the working contact o't armature .211 and said armature, and the resting contact of arma ture 21T and said armature. Magnet 22o now energizes and advances the wipers 229 and 2550 ot the master digit control switch MDC into engagement with the second set et' bank contacts. Relay 203, upon decnergizing, opens the circuit of magnet 2:26 at armature Q11.

lVhen the next digit '3 is sent out by the director. the wipers of the second digit reg ister Dil-t are advanced inttf engagement with the third set of bank contacts by be three impulses of current transmitted over the operating conductor through wipers 2:5) and the second associated bank contact. At the end 'of the series of impulses wipers the seconda-ry switch SS at relay50 dcenergizes; unites thel and 230 of the switch MDCy are advanced into engagement with the third set of bank contacts -in the hereinbefore described manner.

Similarly. thewvipei's ot the. third digit register DRE' are advanced into engagement with the ninth set of bank contacts in response to the sendingout of the third digft 9 in the subscribers number by the director, after whichl the wipers of the master digit 1 control' switch MDC are-advanced into en-' gagement with the fourth set of bank con tacts in the manner described above.

When the fourth digit 0 in the subscribers number is transmitted by the director, the ten impulses sent over the operatmg conductor by the line relay of the /repeater R cause the wipers of the fourth digit register DR3V to be advanced into engagement with the tenth set of bank contacts, after which the wipers of the master digit control i switch MDC are advanced into engagement with the fifth set of bank contacts.

en the director sends out the .station digit W, which digit is numerically equivalent to the digit 9, nine impulses of current are transmitted to the operating magnet of f the station register 'SR .in the usual manner.

Conse uently, the wipers of the station register S are advancedinto engagement with the-ninth set of bank contacts, after which the 'wipers of the switch MDC are advanced mto'. engagement with the sixth set of bank contacts in the above described manner.

In the director, Fig. 1 switching relay 75 energizes after the last digit has been sent ont and places ground on conductor 70 at armature 79, whereupon switching relay 30 in the trunk circuit TC energizes over a circuit which includes condnctor 70, bank eon- ,tact 66, wiper 62, working contact of armature'58 and said armature, and armature 30 andts working Contact. Upon energizing, relay 30 locks itself to release trunk conductor 20 at armature 35; disconnects line relay 3l at armatures 34 and36; unites conductors 19 and 21 with conductors 42 and 44, respectively, at armatures 33 and 37';l and at the normally closed contacts controlled by armatures and 37 disconnects the local bridge controlled by repeating relay 32 from across conductors 42 and 44, leaving the line relay of the repeater R, to which the connection has been extended, under the direct control of the calling loop. Line relay 31 of the trunk circuit TC, upon deenergizing in response to being disconnected by relay 30, opens the circuit of slow acting relay 50 of armature 38, whereupon conductors 20 and 42 and removes the .local ground connection/,from conductor 20 at armature 53; and at armature 55 opens the circuit of relay 51,` whereupon relay 51 leenergizes and disconnects its wipers. The d1- lrector now rererts to common the switch MDC. Fig.. 3. upon use and is restored to normal in the usual manner. i

Returning now to Ithe coder, wiper l230 of d coming into engagement with the sixth associate'rl'bank contar-t as above descril'ied, closes a circuit for the upper winding ot' relay 205 by way of the resting contact oi' armature 220 and said armatureY Relay 205, upon energizing, closes a locking circuit for its lower winding over the outgoing impulseconductors 153 and 154 at armatures 216 and 216, and at armature 215 closes a circuit for relay 206. Relay 206, upon energizing, closes a point in the circuit` for placing ground on start conductor 241 at armature 218; disconnects magnet 226 at armature 21T; closes a locking circuit for itself at armature 219,.and at armature 220 opens the initial circuit of relay 205, leaving relay 205 energized by means of its lower winding.

In the manual ofiice line relay 302 of the cord circuit O, Fig. 5, energiz'esY over conductors 130 and 131 in response to the lower resting contact of armature 317 and said armature.

The operatorupon noting the lighted cOni dition of the lam L depresses tlie\assign ment key K individual to the trunk, thereby grounding'the locking conductor 311.015 her" call indicator set and closinga clrcuit for relay 301. Relay 301,- upon energizing, dis? connects conductors 130 and 131 from 'the windings of the repeating coil and extendsA them to relays 325-327, inclusive, by way of conductors 309 and 310. 'Incidentally 'line relay 302 dcenergizes and the lamp cornes extinguished. Y

In the automatic'ofliee relay 205 of the coder, Fig. 3,- dcenergizesin response to the circuit change produced by relay 301, Fig. 5, as described above; disconnects itself Vfrom conductors 153 and 154 at armatures 216 and 216'; and at armature215 places ground on start conductor 241 byway of the working contact of armature 218 and said armaturel When ground is placed on the start conductor 241, start relay 249, Fig. 4, energizes; disconnects wipers 269 and 270 of the sender Afrom stepping magnet4 250 at armatures 264l and 265 and connects them to the lower winding of relay ,247. and the winding of relay 248, respectively; disconnects ground from certain contacts in the bank ot' wiper 269 at armature 266; and ncets' sending relay 245 to the intermittently grounded conductor at armature 266 con-v associated with the contacts, relay 246 energizes advanced into engagement with. the third set ot bank contacts, whereupon relay 248 energires and prepares a circuit for sending lay 245, the light negative impulse is sent out over the following circuit: from grounded battery` by Way of' resistance 263, Working Contact of armature 262 and said armature, resting contact and said armature, previously traced vcircuit to armature 251, armature 251 and its working contact, and armature 261and its Working contact to ground.

Upony the following deenergization of relay 245. the light negative impulse is terminated at armatures 251 and 252, and magnet 250 advances the Wipers of t-'he sender into engagement with the lfourth set of bank contacts.y With the wipers of the sender in engagement Withthe fourth setvof bank and prepares the 'circuit at armatures 254 and 255 for sending out the heavy negative impulse in the first digit 2 of the subscribers number. The circuit of relay 246 is as follows from ground by Way of right-hand Wiper 232l` of'the digit register DR, the second associated bank contact, the associated conductor, the fourth contact in the bank of wiper 267 of the sender S andsaid wiper, and relay 246't battery. 1

V'Vhen relay'245 energizesagain, the heavynegative impulse is sent out in the previously described manner.

Upon the subsequent vdeenergization of relay 245, the heayy negative impulse i's terminated and the Wipers of the sender are advanced into engagement With the fifth set of bank contacts. With the wipers'ot. the sender S iu engagement with the fifth set ot bank contacts, none of the impulsing circuit preparing relays 246-249, 1nclusive, are energized and no impulse is sent when relay 245 energizes.

Upon the following deenergization of relay 245, the wipers'oi the sender S are advanced into engagement with the lsixth set of bank contacts, whereupon relay 248 energizes through the sixth Contact in the bank of n'ipen270 and said wiper, and thence `over (he previously traced circuit and pre- .pares the impulsing circuit for sending ont the light negative impulse' of the digit 2 at armatures 261 and 262.

Upon the next energization of relay 245 the Ylight negative impulse is sent out at in the' bank of Wiper 270 and of armature 255 and said armature, working Contact of armature 252A armatures 251 and 252, as hereinbefore described. I y f Ilpdn the following deenergizatio of relay 245, the Wipers of the sender are advanced into engagement with the seventh set of' bank contacts, whereupon relay 247 energizes over the following circuit.: from ground by way of the right-hand wiper of the digit bank contact. the associated conductor, the

seventhv contact in thebank of wiper 268 and said wiper, andthe upper winding of relay 247 to batteryv- Relay 247,. upon energizing, prevents the ener ization of relay 248- at armature 260, an at armatures 25T and 258' prepares the impulsing circuit -for'sending ont the light positive impulse .register DR", the third associated ofthe second digit 3 in the subscribers num ber. Consequently', the light positive iinpruls'e is sent out upon the following energization of the sending relay 245. V Vhen t-he 'Wipers of the sender are" advancedinto engagement with the eighth set of bank contacts uponv the following deenergization of relay,- 245, relay 246 energizes over the following circuit: yfrom ground by Way of theright-hand Wiper of the digit register DR. thev third associated bank contact, the associated conductor, eighth contact in the'bank of the Wiper 267 and said wiper, and relay 246 to battery. Relay 246, upon energizing, prepares' the impulsi-ng circuit for the sending out oi the. heavy negative impulse oi the seconddigit 3 in the suhscribers number. Consequently, the heavy negative impulse vis sent ont upon the next energization of relayY 245.

fUpon the following de'energization of relay 245, the wipers of the sender Sfaie advanced into engagement withithe ninth set ofharik contacts,whereupon relay .248 energizes through the ninth contact in the bank otwiper 270 and said wiper and prepares the impulsing circuit Vfor sending out the light negative impulse ofthe second digit 3 in the subscribers number. Consequently, .fthe lightnegative impulse is sent 'ut'upon the v'following energization of 'the'sending relay 245. y Upon the next deenergization of relay 245, the wipers ot the sender are advanced into engagement with the tenth set of bank contacts, whereupon relay 24S energizes through the tenth contact in the bank of wiper 270 and said Wiper, and the light negative im'- `pnlse ol the third digit 9 in the subscribefs number is sentent upon-thc next energization of the sending relay 24.

.Upon the next deenergization of i relay 245, the wipers ot theI sender S areadvanced into engagement with the eleventh set of bank contacts, whereupon relay '247 enerthe third digit register DB2, the uint,v vcon` lll) `tact the bank thereof, the associated conductor, the eleventh contact in the bank of wiper 268 and said wiper, and the upper ,winding of relay 247 to .iattcry. Relay24i',

upon energizing'.

prepares the impulsing circuit for sending out the light positive inipuls'gof the third digit 0 iii the suhscribers number. and the light positive impulse is sentout upon the following energization of sending relay 245.

AVi'vhen the wipers of the sender S are advanced into engagement with the twelfth Set'of bank contacts upon the following deenergization of sending relay 245, relay 24,6 is energized over the following circuit: froiu ground by way of the left hand wiper of the third digit. register D112, the ninth contact. in the bank thereof, the. associated conductor, the twelfth contact. in the bank of wiper 207 and said wiper, and relay 2110 to battery. Relay 24.6,'upon energizing, prepares the iinpulsing circuit for sending out the heavy negative impulse of the third digit t) in the subserihers number, and the heavy negative iinpiilseis sent out upon the. next energizetioii of the sending relay Vhen the wipers of the sender are advaneed into engagement willitlie thirteenth set of bank contacts uponthe next deenerg'iation of sending,Y relay 245, relay 2-'1-0 ener- ;rizes throughthe thirteenth contact in thel bank of wiper 270 and said wiper, and prepares the impulsing circuit for sending out a light 'negative impulse. Consequently, the first light negative impulse in the fourth .digit 0 in the subscribers number is sent` out upon the next enei'gizationof the sendingI relay 245.

lVlien the wipers of the sender S are advanced into engagement with the fourteenth set of bank contacts upon the next deencrgri.- Zation of sending relay 245, none of the impulsing circuit preparing relays 246-248, inclusive. are enerffized, the wipers of the digit regis-ter DR being in engagement with the tenth set of bank contacts. Consequently, no impulse is sent out upon the following energization of sending,r relay 245. f

lVhen the wipers o1 the sender S are advanced into engagement with the fifteenth set of bank contacts upon the following de.- energization of sendingrelay 245, relay 2118 energizes through the fifteenth contact in the bank of wiper 270 and said wiper, and prepares the inipulsing circuit for sending out a light'negative impulse. Consequently, the .second light negative impulse of the fourth digit 0 in the subscribers number is Vsent out upon the next encrgization of sending relay 245.

When the, wipers of the sender S Yare advanced into engagement willi the sixteenth set of bank contacts, upon the following deenergization of sending relay 245, wipers.

267 and 268 encounter grounded contacts,

whereupon relay 24:6 energizes through wiper 207 and relay 247 energizes through its upper winding and wipe'r 26S. lViper 270 also is in engagement with agroundml v contact, and since, relays l216 andA 247 are ture 120 ot' line rela;7 lll and its working con' tact. and switching` relay 116 to battery, Switching relay 316, upon energizing, opens the circuit of switching relay 130 of the Secondary switch SS and closes a locking circuit for itself at armature 128, disconnects the tone condenser' l126 at armature 127, and at armatures 125 and 129 disconnects condiictors 1.30 and 131 from-the'impulsing eircuitI extending' to the coder and connects them to a closed bridge which includes the upper windingv of electii -iifilarized relay 1133 and impedance 11T. This operation also places conductors 1230 and 131 in talking relation to conductors 110 and 112 through the heavy talking condensers of the repeater R. ,lt will be understood that the operation of switchingl relay 116 occurs soon enough to disconnect conductors 13()v and 131 from the inipiilsing circuit before the next energizalion et sending relay 245, Fig. It.

Sii'itchiiugr relay 136 of the secondary switch SS, upon deener,r ,ifizingr in response to the opening of its circuit by switching' relay lll of the repeater Ras pointed out above. disconnects its wipers at armatures liti-144, inclusi-re,.thereby ,removing ground from releasev trunk conductor 155. vWhen this occurs, release relay 201, Fig. 3, deenergizes and opens the circuit ot' relay 206 at armature `200. Relay 200, upon `deenergizingr, removes ground lfrom start conductor y 241 at armature 21S, whereupon relay 21S), Fig. 4, dcenergizcs; disconnects sending re- 'lay 245 at armature 200'; places ground at armature 200 on the contacts in the-bank of wiper 26S), corresponding to the ungrounded contacts in the bank of wiper 270; and at armatures 264 and 205 connects Wipers 269 and 270 to stepping magnet 250 through the local interrupter contacts of' said stepping Amagnet 250. Then this occurs, the wipersof the sender S are spun to .normal position by the buzzer-like action of stepping magnet 250, which magnet buzzes only as long as either wiper 209 or wiper 270 is in engagement with a grounded contact.

As a further result of the dcenergization of release relay 201, Fig. 3,'itplaces ground on release conductor 224 at armature 209,.

' responding series is heavy.

with 4 is operated by marginal relay 32T in oase the second negative impulse of the cor- In, this ease, since the numerical part of Y the termination of the last impulse in the curs, sleeve relay units digiti), it places ground on conductor 330 at armature 376, whereupon the called number is displayed on the operators indicator lamps.

After the operator has noted the number set up, she releases the assignment key K, thereby removing ground from conductor 311, whereupon t ie various energized relays controlled by conductor-311 deenergize an the lighted indicator lamps become extinguished. As a further result of the restoration of the key K the circuit ot' relay 301 is opened. Relay 301, upon deener gizing, disconnects conductors 130 and 131 from conductors 309 and 310 at armatures 304 and 305 and extends them again to the windings of line relay 302, whereupon line relay 302 agam energizes and lights the lamp L. The circuit of line relay 302 at this time includes impedance 117 and the upper winding of electro-polarized relay 113 of the repeater R. Relay 113, however, is not energized at this time on account of the fact that the current flow in each winding is in such a direction as to tend to neutralize the effect of the current flow in the other wind mg.-

The operator now tests the usual manner by tapping the tip of her plug P against the sleeve of the jack J, and, assuming the line to be idle, she inserts the said plug into `the said jack.

313 of the cord circuit 4O and the cut-off relay of the called line en ergize in series, the latter relay performing the well known function of clearing the line of its attachments. Sleeve relay 3,13, upon energizing, extinguishes the lamp 'L at armature 317, and disconnects the operators head set from the ti vof the plug P and connectsV up the tip an ring conductors of the cord circuit 'to armatures 314 and 315 of 'ring cut olf relay 312, respectively. The o erator now throws the proper one of the our ringing keys K-K, inclusive, the key K', for example, whereupon'ringing current of the proper frequency to ring the bell ,at substation A is projected outover the called line.

Then the called subscriber responds to the ringing of his bell by removing his receiver, a direct current bridge closed the @nieu une inI 'When this ceacross the conductors of the` called line, whereupon ring cut o relay 312 energizes through its upper winding; removes the shunt fromaround its lower winding at armature 319, so as to maintain the said relay energized independent of its upper winding; and at' armatures 311 and 315 disconnects the tip and ring conductors vof the cord circuit from its own upper.

winding and the source of ringing current and extends them through the righthand windings of the repeating coil to the windings of back-bridge relay 303. lBackbridge relay 303, upon energizing, reverses the current flow in conductors 130 and 131 at armatures 30T and 308. When this occurs, the electro-polarized relay 113 in the repeater `R energizes and reverses the current flow in conductors 110 and 112 at arma tures 118 and 119. This reversal has no particular function, in the present case but is used in other cases for various purposes, such as, for example, to operate a subscribers meter when a subscriber is calling who has a meter individual to his line either at the substation or at the central office. The two subscribers may now converse with each other as desired, the talking circuit-s being outlined by the heavy conductors, and when they have finished they replace their receivers.

lVhen the receiver is replaced at substation A back bridge relay 303 in the cori circuit O deenergizes and reverses the current flow in conductors 130 and 131,to normal.- whereupon relay 113 in the repeater R deenergizes and reverses the current flow in conductors 110 and 112 to normal.

l/Vhen the receiver is replaced at the calling substation A, the circuit of relay 114 of .the repeater R is opened. Relay 114, upon deenerfrizing, opens. the circuit of slow acting re ease relay 115 at armature 124. Release relay 115, upon deenergizi'ng, opens the circuit of the lower winding of electropolarized relay 113 at armature 121,1; opensthe circuit of relay 116 at apriatur'e 122, where-A upon-the relay 116 deenrgizes; and at armature 123 removes ground from release trunk conductor 111, whereupon the selectors E and F are restored to normal position in the usual manner. the selector E, for example, being restored to normal by release magnet 85 upon the closure of its circuit by armature 98 of switching relay 34. The circuit of release magnet 85 is opened at the off' normal contacts 87 by the switch shaft when the latter reaches normal position.' As

a further result of the removal of the ground potential from the release trunk conductor 111` switching relays 5 and 30 of the line switch C and the trunk circuit TG, respectively, deenergize, thus restoring conditions in the associated circuits to normal.

As a result of the deenergizaton of relay closes 1G jack J, whereupon the associated relays det the repeater R, the bridge is removed rom V1 1 y c 1 I o ne manual oilice, whereupon line relay in the cord circuit O -deenergizes and at armature 306 a circuit tor the lamp L by 'way ot' the working contact ot' armature 317 and said armature. llYhen the operator notes the lighted condition of the lamp L she removesthe plug P trom the energize, and the lamp ,L becomes extinguished. n

Assuming that the subscriber at substation A makes another call and that he is calling a subscriber in a manual otlice in which no party line designation,

there are'no party lines, and consequently the director in use,

governed by the oiiice digits of the number i as is disclosed in the Nelson application hereinbetore referred to, sends out the digit 1 advancing the master after the call has' been trunked to the desired manual oiiice and the tour digits of the 'subscribers number have been sent to the coder in use. Assuming that the coder used is the one showin-in Figs. 3* and 4, which coder, it will be understood, isaccessible to secondary switches such as the secondary switch SS", Fig. 2, associated with trunks leading to straight line manual oiiices as well as to secondary switches associated with trunks leading to party line manual ofiices, the digit 1- l` has the eiiectof stepping the wipers of the station register SR Fig, into engagement 'with the firstset ot baiilccontacts, and 'of digit, control switch MDC into switching first set ot bank contacts of the station register SR are dead` the two light' negative ini- Apulses for which the sender is normally set hare sent'out ahead ot the subscribers number. This hasfthe eltect of connecting up the operating circuits to the thousandsset ot' relays in the straight line call indicator in use, the stations set ot' indicator lamps be,-

\ing omitted in 'the straight line call indicators. i Gtherwis'ethe call indicators, torthe sake of uniformity, are made the same tor both thestraight line and the party line otlices.

Referring now to Figs. 2 and 3, the method of giving a calling subscriber a busy tone in case no coder is available when he calls will be explained. The individual test contact 159 in the set-ot overflow contacts 15T-1GO, inclusive, in the bank of the lsec-l ondary switch SS, Fig. 2, ot which there is only one set provided t'or veach switch, is norn'ially grounded by relay 164e as are thev similar contacts in thc'banks of each of the other coder selecting secondary switches. This, of course, makes the setof contacts test busy and ordinarily none of the secondary switches stop on the set ot overflow contacts. However, assuming that all the coders become busy, ground is removed fromA o oss conductors 180 and 131 leading .established connection position. Since the conductor 163 at all points corresponding toI the test contacts such as test contact 159.

Then, assuming the secondary switch SS to be hunting for 'a coder at this time its wipers are rotated past the contacts in whicli the trunks extending to the busy coders terminate and are stopped in engagement with the 'overflow contacts 157460, inclusive. When switching relay 13G energizes at this time, as it does in the hereinbetore described manner, it connects up wiper 148 at armature 141i, whereupon busy signalling` current is applied to the upper talking conductor over a circuit which extends as grounded battery by.l way ot the lett:l hand winding of the busy tone transformer, the associated condenser, bank contact 160, wiper 148, armature 144 and its working contact, condenser 126, and armature 127 and its resting contact to the upper heavy talking conductor. This busy tone informs the calling subscriber that he cannot obtain the de` .sired connection forthe time being.' Upon hearing this busy tone the calling subscriber replaces his receiver, whereupon the partly is released in the usual manner.

I claini': A

l. In a telephone system, a set ot' register switches for registering' the digits in a-telephone number, a set ot relays 'for transmitting impulses in accordance with a nondecimal code, and inc-ans inc linliug u rotary switch for controlling said relays in accordance` with the setting vo t said switches.

2, ln a telephone, system, a set ot rcgiste switches for registering the digits in a telcphone i'ilunber, a set ot relays tor transinitl ting impulses in accordance with a nondecimal code, .means including a rotary switch for controlling said relays in accord-I ance with .the setting. of said register sw1tches,a visual mchcator torindicating say ters, means for energizing said preparing relays in permutations' ting of each of said registers in turn, means according to the set- 'i including' a circuit closing relay for closing the circuits prepared by said circuit preparing relays, and means for. energizing said circuit closingrrelay after each ener-fixation ot the circuit preparing relays.

5. The combination, with a metallic circuit, of means for transmittingr heavy and light impulses over said'circuit, the light impulses being of either polarity, said means comprising permutational relays for preparing the circuit, a circuit closing' relay for closing the circuit each time after it is prepared, and means tor energizing` said relays a plurality of times to transmit a code representing the digits in a telephone number. A

6. The combination, with a metallic circuit, of means for transmitting heavy and light impulses over said circuit, the light impulses beiner of either polarity, said means comprising permutational relays i'or preparing the circuit, a circuit closing' relay for closing the circuit each time after it is prepared, and means including' a rotary step by step switch 7. In a multi-office vtelephone system. a step by step automatic oice, a. manual oflice, an operators switchboard .in said lmanual office, trunk lines leadingI from said automatic office to said manual olice and terminating thereat in said switchboard, a, plurality of coders in said automatic oice comprising registering and transmitting means, means responsive to a seizure of one of said trunk lines in said automatic oliice for connecting such trunk line to an idle one ot said coders, means for operating;` the registering means of such lcoder in accordance with' the number of the desired manual line, means effective thereupon for signalling the operator at the switchboard in the manual ofiice, and. means controlled by the response of the operator at such switchboard for operatingr the sendingY means ot the coder in use to transmit codedimpulses over the said seized trunk line to indicate to the operator A the desired number.

for enereizint said relays.v

8. In a multi-oilice telephone system, a step byv step automatic office, a manual otlice, an operators switchboard in said manual olliee. automatic oflice to said manual otlice-and terminating thereat in said switchboard, plurality ot coders in said automatic -oiiice :oi'nprising registering and transmitting apparatus. incans responsive to the impulses representing the part ot a called number indic-alive ol said manual otiice for operating switching mechanism in said automatic oilice to seize one of said trunk lines, means responsive to such ,seizurev for connecting the seized trunk line to an idle one of said coders, means jtor operating the registering means ot' each coder in accordance Wit pulses representing the portion of the called number indicative of the desired manual line, means etl'ective thereupon for signallingA the operator means controlled by the response of the operator l'or rnierating the sendingnieans of the coder in use to transmit code impulses trunk lines leading from said.

at the said switchboard,

ores' the said seized trunk line to indicate i to the operator the desired number.

vS). The combination of a step.-bystep de-` vice tor transmitting` impulses of different characters on succeeding steps of the stepby-step device, of a circuit through which the impulses are transmitted, and a relay energized molmmtarily upon each step of the device to close said circuit.

10. The combination in a step-bystep device for transmitting impulses of different characters on succeedingr steps of the stepby-step device, of a. circuit through which the impulses are transmitted. a relay energized momentarily upon each step o f the device to close said circuit. and means including contacts on said lrelay for controlling the step-by-step movi-ment of said device.

In witness whereof, I hereunto subscribe my name this 13th day of October, ALD., 

